How to detect if USB keyboard is plugged and unplugged

Question

Is there any daemon/tool which will trigger some signal/event when USB keyboard is plugged and unplugged from pc? I need to know in my program when USB keyboard is plugged and unplugged. Any ideas on how to do this?

Answer 1

udev (Linux device manager) is the one that polls hardware. When it detects some changes about devices, it executes the rule associated.

You should add a rule to udev, in order to inform your program about insertion of removal of USB keyboard. You can find documentation about udev rules here, or Look at files in /etc/udev/rules.d/ or /lib/udev/rules.d/ to find many examples.

Answer 2

udevadm monitor (the udev administration binary) or udev_monitor (in libudev).

Alternately, if you're running in X11 with input hotplugging, you can listen for the XI extension event DevicePresenceNotify.